Aggregate for concrete.



min 0R PlASTlC UNITED STATES i- AGE PATENT OFFICE.

FRANK ll. HALDEIMLAN, OF CLEVELAND, OHIO, ASSIGNOB TO THE MASTER BUILDERS COMPANY, OF CLEVELAND, OHIO, ll CORPORATION OF OHIO.

AGGREGATE FOB CONCRETE.

1,113,555. Io Drawing.

To all whom it may concern:

Be it known that I, FRANK M. I'IAIDEMAN, a citizen of the United States, residing at Cleveland. in the county of Cuyahoga and State of Ohio, have invented a certain new and useful Improvement in Aggregates for Concrete, of which the following is a full, clear, and exact description.

This invention relates to cement or concrete structures and has for its object the production of a material whereby the surface of such structure may be hardened, toughened. solidified and rendered impervious to liquids, and also whereby a new layer or section of concrete may be efficiently bonded to a previously existent structure of similar or dissimilar material.

It has long been noted that concrete on account of its porosity is hi hly afl'ected by climatic changes, particular y y the action of water, and accordingly expands and contracts markedly, frequently becoming cracked and broken by the strain. Also this porous condition renders the mas friable and causes the formation of a large amount of dust in case the concrete structure be subjected to heavy trafiic as in the case of floors, walks. and roadways. Besides the capacity of ordinary concrete for absorbing and transmitting moisture is frequentl objectionable. It is well known that t e finer grained aggregates will ordinarily produce a less porous concrete than the coarser aggregates, but this fineness can be carried successfully only to a certain point in the case of silicious aggregates since the ver fine sands (by which I mean those whic will pass through a sieve having fifty holes to the linear inch) are almost always of a very smooth and glassy surface, frequently even having their edges ground away by attrition, so that it is impossible to secure such adhesion of the cement as shall result in a durable concrete. The few mineral compounds which retain an irregular surface or hackly fracture after being finely pulverized are either so friable mechanically or so impermanent chemically as to be unavailable.

It has heretofore been proposed to employ with the cement an aggregate consists ing of finelv divided metallic iron particles owing to the fact that these iron particles I Specification of Letters Patent. Application filed Kay 4, 1814. Serial No. 888,888.

Patented Oct. 13, 1914.

- are of very irregular formation and the cement adheres to the same with great tenacity. Experience'has shown that a cement of this nature when properly mixed and of fresh, standard materials and applied in a thorough and careful manner is permanent. over long eriods' of time and without any appreciab e oxidation or deterioration of the iron content. However, this iron material is ordinarily obtained by sifting the iron waste of machine shops "and is con uently more or less mixed with oil so that it is very difficult to'wet the same pr rly with water, or to obtain the proper a hesion of the cement thereto. Also the rusting of the particles is certain to be avoided only in case the particles are carefully and thoroughly incor rated with the cement which is impeded y the oily film with which the particles are covered.

It is the object of the present invention to provide an aggregate which shall have all the fiheness and irregularity of the iron particles heretofore mentioned; which shall be more easily wetted with water during the process of mixing than the iron above mentioned; which shall be less liable to oxtioned; and to which the cement will adhere with a greater strength than to other aggregates; while further objects and advanta scription proceeds.

-I have discovered that iLfiElLQTUfihQ ges will become apparent as the de- 5 metallic iron particles be agitated in con tact with Emit temps-mine d'fffiin" 799 to 900 C. for a few minutes,the oily matters wnll be'ehtirely driven oil and the surface of each grain will be covered with a very thin film of ma etic oxid which will adhere verv fen'aciouslv To the cement and which will efi'ectively inhibit any further oxidation of the particles. The operation is a kind of roasting process and causes a change in color of the particles from the gray of metallic iron to a kind of bluish black. Micro'scopic examination shows each particle to be covered with an iridesgnt film of gxid, the play of colors in icatlng t at the the ness of the oxid film is of the order of magnitude of the wave lengh of light.

In the preparation 0 my improved aggregate I obtain clean iron boriggg fillEES,

or tu 'n s and sift them through a screen of 15 to 20 openings to the linear inch. .The part that fails to pass through this sieve can be partially recovered by crushing or pounding or it can be discarded. The sifted material is then spread u on a large fire brick bed and roasted in contact with the air for a period of from five to fifteen minutes. The material is raked out to form a layer from two to four inches deep and is re-raked or turned over every few minutes during the roasting operation. It is found that any long quiescence causes a caking together of the mass and a formation of ferric sesquioxid Fe O instead of the ma etic 0x13 'iFe,U,$. firWt of the roasting operation large quantities of oil-smoke are evolved, which maybe caught in a hood and carried away. It generally takes from three to five minutes to eliminate all the oil and about ten to twelve minutes at the temperature indicated to oxidize the particles the desired amount. Doubtless the rapidity of oxidation would be enhanced by preheating the air or by projecting the particles directly into an oxidizing atmosphere, but I prefer to conduct the process slowly and at the lowest feasible temperature since none of the iron must be permitted to turn to ferric sesquioxid and only a very thin film of the magnetic oxid is desirable. Ferric sesquioxid is a loose friable powder and has no stren h in connection with cement. Also it is ine ective to inhibit further oxidation and is even thought by some to encourage oxidation. The magnetic oxid, however, forms a thin continuous skin over the metal and prevents the access of moisture and oxygen thereto. Also if care be taken that this be confined to a thin film it will not exhibit an tendency to scale away from the metal, while the natural jagged shape of the grains will not be materially obliterated. If the oxidation were to be continued too long a time or at toohigh a temperature the coating of oxid would become too thick and would tend to cleave away from the particles as well as obliterating the sharper edges. For the same reason I prefer to remove by sifting or by suction the smallest particles of the iron borings such as those smaller than 1/200th inch in diameter, since the tendencv of these is to become too far oxidized during the roasting process. The poper condition of the particles can readily determined by a microscopic investigation since they should possess an irridescent luster due to a thinness of magnetic oxid film about e ual to the wave length of li ht and should a so cases an irregular sur ace not noticeably literated by the oxidation. The aggregate thus produced will be found to absorb water with great avidity, mix with cement very readily and resist further oxidation for long periods of time. It is used by mixing with ement and water in the usual manner ana is applied either as a bonding coat to secure new concrete to old concrete or as a finishing coat to the surface of new concrete, or even by mixin directly with cement and sand 'n the pro uction of the concrete as in ie case of any other aggregate. However, the use for bonding and for surfacing are most important since these uses afford the maximum of utility comared with the amount of material employed. For use in bonding, I prefer to mix equal parts of my improved aggregate together with a fresh alkaline cement and wet with water to form a thin aste which is immediately brushed or t rown upon the surface of the original concrete and followed immediately with the new concrete which is to be secured thereto.

For surfacing concrete I prefer to dust upon the face of the concrete immediately after it is laid and before it has set, a dry mixture of this aggregate and fresh alkaline cement in substantially equal parts, then to float the same into the surface of the concrete until the dust coat has been thoroughly \vetted with water from beneath and until the particles of aggregate are thoroughly coated with the pasty cement, then to trowel thoroughly the surface so produced, re eating the troweling at different stages 0 the setting so that the surface may be thoroughly compacted and the cement forced snugly into contact at all points with the surface of the iron particles. This produces a coating of great beauty, luster, hardness, smoothness and wearing qualities and is proving useful for docks, warehouses, factories, libraries. stores, and ofiices as well as for roofs. walls and roadwavs.

While I have described my invention in detail I do not. confine myself to the mechanisms, times, or manipulations herein suggested or to the particular uses mentioned, or in any other way except as specifically limited in the claims hereto annexed or as rendered necessary by the prior state of the art.

Having thus described my invention, what I claim is 1. A composition of matter containing cement, water, and finely disintegrated metallic iron particles, each of said iron particles having upon its surface a thin filmiform coating of magnetic oxid of iron.

2. A concrete structure having its surface portions formed of cement and finely disintegrated metallic iron particles, each of said iron particles being covered with a thin. substantially uniform filmiform coating of magnetic oxid of iron;

3; A concrete structure having its surface 106. COMPOSHIUNS, M1 55 H I HUU Lxamm COATING OR PLAST'C portions formed of finely disintegrated In testimony whereof, I hereunto afix my meltallilfe iron particiies, each of irogspzrsignature in the presence of two witnesses. tices ing covere with a t su n- 1 v tially uniform filmiform coating of magnetic FRAhh HALDEMAN' .5 oxid of iron, and adjacent iron particles be- Witnesses:

mg surrounded and spaced apart by a ma- Harrow E. Snrrn, tux of set cement. T. A. Bnmcn. 

